During August 1941, TsAGI proposed the installation of trapezoidal
wingtips on the MiG-3, that, according to wind tunnel tests, should decrease
the landing speed of about 5 km/h; this modify was rejected, because such
a small improvement couldn't justify trouble in a full working assembling
line.
The photo shows a mockup with trapezoidal wings, ski landing gear and
stripes on a T-101 wind tunnel.

MiG-7 (izdelye 72)

During April 1941, the engine AM-37 was approved for series production.
A MiG-3 equipped with an AM-37 engine was built and named MiG-7.
Test pilot N.P.Baulin and chief engineer V.N.Sorokin were assigned
to its factory tests.
The first flights revealed a poor longitudinal stability, that would
require wide reprojecting of the aircraft.
The AM-37 engine was removed from the MiG-7 to be installed on the
DIS-200 (MiG-5) heavy fighter prototype.
The beginning of the war led to abandoning the project, because of
the priority of AM-38F production for Il-2s.

MiG-3 AM-38

One weak point of the MiG-3 was its poor performance at low altitudes,
where the most of air combat took place.
To remedy to this, the aircraft n.3595 was equipped with an AM-38F
engine with a takeoff power of 1600 hp and a AV-5L-110A propeller.
The aircraft made its maiden flight on July 31, 1941, and conducted
tests for the following 12 days. Test pilots Y.K. Stankevich and chief
engineer K.N. Mkrtychan were assigned to the test program.
The greater power improved by much the aircraft's performances, particularly
maximum speed, up to the altitude of 4,000 m.

The aircraft was tested in two configurations:

the first one was the original made by Zavod 1;

the second one incorporated some modifies proposed by the chief designer:
new design of the fairings of the exhaust stacks, bomb shackles removed
and inert gas system installed.

In the first configuration the aircraft reached 582 km/h at 3400 m altitude,
while in the second configuration it reached 592 km/h.
While the AM-38 F engine could easily replace the AM-35A without structural
modifies, the cooling system revealed to be unsufficient for this more
powerful engine, and this limited the operability of the aircraft to temperatures
not higher than 16°C on the ground.
After the test in NII, the aircraft returned in Zavod 1 for modifies,
but after this the aircraft gave problems with the supercharger, and during
a flight the aircraft suffered deformation of fuel tanks. After 22 flights,
on September 22 the aircraft returned to the factory for repairs.
On October 4 the aircraft flew again on the airstripe of Zavod 1, but
the following day the aircraft crashed killing the test pilot N.P.Baulin.
An investigation showed that the cause of this was a combat with an
enemy aircraft.
Due to the shortage of AM-35A, some units conducted their own experiment
on the use of AM-38. Two aircrafts of 402 IAP were modified in such way
during November 1941, and were tested by the regimental commander Major
K.A.Grudzev, and squadron commander captain B.G. Boroday. The first of
them shot down two enemy bombers while testing the modified aircraft n.
4184.

Photo-reconaissance MiG-3During July 1941, five aircrafts were modified in Zavod 1 with the
installation of an AFA-I camera.

Lightened MiG-3In 1943, two MiG-3s were modified by NII-VVS to increase their ceiling.
One of the aircrafts was lightened of 187 kg, passing to a loaded mass
of 3098 kg; its ceiling increased to 11750 m.

Pressurized MiG-3 (project XS)Before the war, a pressurized cockpit was required for I-200 and I-153;
the chief designer of Zavod 482, A.Y. Tserbakov developeed three versions
of the pressurized cabin. Due to the starting of the war, the project was
abandoned.

MiG-3 SPB for ZvenoThe SPB composite dive bomber, also known as Zveno, consisted of a
carrier aircraft TB-3 with two I-16 fighter armed with two 250 kg bombs
each; the fighters were carried by the TB-3, then they were released for
the final attack and they return back (hopely) on their own or carried
again by the TB-3; this allows to attack objectives by far beyond the range
of an usual bomber.
An updated Zveno considered the use of a Pe-8 four-engine bomber and
two MiG-3s with bombs.
The project was abandoned due to the heavy workload of the factories.
Estimated data:
total mass 33500 kg;
maximun speed with all the engines in action: 405-420 km/h;
Ceiling 8700-8900 m;
Flying range at 5,000 m: 1320-1450 km, with the fighters engines nourished
by the fuel of the bomber;
duration of flight about 5 hours.

MiG-3 with additional wingIn 1941, designer A.A. Senkov proposed to install an additional retractable
canvas wing on MiG-3s to reduce landing speed.
The proposal was not accepted because the increased weight and drag
would deteriorate the flight characteristics.